10 December

1967… NMCB-121 fire fighting party assisted in extinguishing a fire the the village of Phu Long.
…The NMCB-58 Main Body began arriving at Camp Haskins North, Da Nang. The movement was complete on 16 December 1967.
…LCDR L.E. Vann, SC, USN; LTJG G.G. Kasper, SC, USN; and SKC E.A. O’Malley were onboard Camp Adenir to conduct an annual Supply Inspection on NMCB-7. The Battalion was awarded a tentative grade of Outstanding.
…In-Country battalions were often faced with the problems of replacing small bridges which had been destroyed. On National Route 1 the bridges to be replaced were generally in remote, insecure locations. The sites were temporally spanned by Marine balk bridging and it was desireable to replace the destroyed bridge with minimum disruption of normal traffic flow. NMCB-3’s solution to this problem was precast concrete bridges.
North of Hue, NMCB-3 placed the first precast bridge to be used by Seabees in Vietnam. To avoid closing of the road, new abutments were placed behind the original abutments during a night operation after the road was closed. The temporary balk span was removed intact by a mobile crane and placed out of the way. New abutments were excavated by jackhammer, formed and placed using transit mixer concrete. The entire operation was completed in ten hours and the balk span replaced over the fresh concrete.
Stringers and deck panels were formed and placed in a precast yard at Camp Wilkinson. The bridge components were of two basic structural shapes: a 20” x 23” x 24’ composite stringer and an 8” x 3’ x 24’ reinforced concrete deck section. The total number of components required for bridge construction were five stringers and eight deck panels. Two of the five stringers were cast with an integral 8” x 24” reinforced concrete curb to act as a step to affix the deck panels, which were placed perpendicular to the stringers. All components weighed ten tons each, and the deck paneling weighed 3.1 tons each. The monolithic abutments were formed with individual recesses to seat and retain each stringer. Tolerance for the stringer seats was ¾” greater than the width of the member and 1 ½” in the longitudinal dimension. A 1 ½” tolerance between curb sections was adhered to in placing deck panels. It was recommended of future installations that 3” tolerance be used in placing deck panels in this type of design.
After the abutment cured, the road was secured for three hours to permit placing of the precast span. During this time the balk span was again removed, the abutment forme stripped, the precast span placed and the approached backfilled. All bridge components were hauled to the site on three lowboys and set in place with a 25-ton mobile crane.
The precast bridge solution proved extremely effective in this situation and provided two primary advantages: the time that the road was closed to traffic was held to a minimum, and on site crew time was reduced to a minimum making elaborate security arrangements unnecessary.

1968…Two NMCB-3 vehicles were caught in an ambush at the Hai Van Pass. No personnel casualties of equipment damage. (MCB-3 DCR ’68-’69)
…NMCB-11 set Condition One at Camp Rhodes from 2150 to 2240.

1969…An enemy satchel charge partially destroyed a village reading room recently completed by Seabee Team 7102 in Phuoc Tuy Province

1970… Seabee Team 0318 deployed to Ben Tre via government aircraft.
…NMCB-3 Detail Equinox returned to Camp Haskins South from Bac Lieu after completing its assignment.
…NMCB-3 Detail Jupiter departed Camp Haskins South for Chu Lai to do shoulder work on QL-1 between Tam Ky and Thanh Quit.

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